<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        a{
            text-decoration: none;
            color: white;
        }
        .one{
            width: 1000px;
            text-align: center;
            height: 40px;
            background-color: #5b82d8;
            margin-top: 50px;
            position: relative;
        }
        .one-a{
            position: relative;
        }
        .rom{
            content: "";
            display: table;
            clear: both;
        }
        .one li{
            display: inline-block;
            width: 300px;
            line-height: 40px;
            color: white;
            float: left;
        }
        .two{
           position: absolute;
            background-color: #b2b2b2;
            width: 300px;
            display: none;
        }
        .two a{
            display: block;
            box-sizing: border-box;
            border-bottom: 1px solid #ededed;
        }
        .one-a:hover .two{
            display:block;
        }
        .one-a .two a:hover{
            background-color: #02e7fb;
            color: #0456f9;
        }
        .one-b:hover .two{
            display:block;
        }
        .one-b .two a:hover{
            background-color: #02e7fb;
            color: #0456f9;
        }
        .one-c:hover .two{
            display:block;
        }
        .one-c .two a:hover{
            background-color: #02e7fb;
            color: #0456f9;
        }
    </style>
</head>
<body>
<div class="one rom">
    <ul>
        <li class="one-a">
            <a href="#">手机</a>
            <div class="two">
                <a href="#">小米</a>
                <a href="#">魅族</a>
                <a href="#">VIVO</a>
                <a href="#">OPPO</a>
            </div>
        </li>
        <li class="one-b">
            <a href="#">电脑</a>
            <div class="two">
                <a href="#">戴尔</a>
                <a href="#">联想</a>
                <a href="#">华硕</a>
                <a href="#">技嘉</a>
            </div>

        </li>
        <li class="one-c">
            <a href="#">电视</a>
            <div class="two">
                <a href="#">乐视</a>
                <a href="#">微鲸</a>
                <a href="#">小米</a>
            </div>
        </li>
    </ul>

</div>
</body>
</html>